It isn't so much that it is unintuitive, for the most part[1], but rather that there are a lot of things to keep track of, and a seemingly innocous change in on

It isn't so much that it is unintuitive, for the most part[1], but rather that there are a lot of things to keep track of, and a seemingly innocous change in one part of the program can potentially result in UB in somewhere far away. And usually such bugs are not code that is blatantly undefined behavior, but rather code that is well defined most of the time, but in some edge case can trigger undefined behavior. It would help if there was better tooling for finding places that could result in UB. [1]: although some of them can be a little surprising, like the fact that overflow is defined for unsigned types but not signed types